Female, and no, I definitely would not try to achieve size zero. I'm at a healthy weight, and besides, the average Aussie women is a size 14 or thereabouts, and I'm a size 8 (US size 4, I think), so my self-esteem in that respect is fine. If I ever feel bad about my appearance, I just go outside and have a look at the average Australian. Besides, most stores don't carry a size smaller than 6, so I can't imagine where I'd shop if I was a size 0.
I just don't like hearing about people who eat, what, 600 calories a day, and idolise superthin models. Wanting to be fit and healthy is one thing, but losing weight for purely cosmetic reasons to resemble an unrealistic ideal is ridiculous. I can't help but think it's pointless. I mean, there are so many other ways to feel good about yourself without turning into a stick.
And no, I don't find it attractive at all. There's something rather frightening about people who are that thin. It looks really unhealthy, for either gender. Aside from the fact that I would never date a guy skinnier than me, I also wouldn't want to sleep with a girl who was essentially skin and bone. I have a friend who stopped going to school for almost a year due to an eating disorder. It's not just the weight loss - they have no energy, their skin looks awful, their nails and hair are all brittle and dead looking - it's just not good.